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From:   Arnd Bergmann <arnd@kernel.org>
To:     Lee Jones <lee@kernel.org>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Jingoo Han <jingoohan1@gmail.com>,
        Helge Deller <deller@gmx.de>,
        Artur Weber <aweber.kernel@gmail.com>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>,
        Benjamin Mugnier <benjamin.mugnier@foss.st.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH] backlight: lp855x: fix unintialized function return
Date:   Fri, 11 Aug 2023 15:15:53 +0200
Message-Id: <20230811131600.2380519-1-arnd@kernel.org>
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From: Arnd Bergmann <arnd@arndb.de>

The function now returns an error code in some cases, but fails to initialize
it in others:

drivers/video/backlight/lp855x_bl.c:252:11: error: variable 'ret' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
        else if (lp->mode == REGISTER_BASED)
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/video/backlight/lp855x_bl.c:256:9: note: uninitialized use occurs here
        return ret;
               ^~~
drivers/video/backlight/lp855x_bl.c:252:7: note: remove the 'if' if its condition is always true
        else if (lp->mode == REGISTER_BASED)
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Since this case should not actually happen, return the -EINVAL code.

Fixes: 5145531be5fba ("backlight: lp855x: Catch errors when changing brightness")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/video/backlight/lp855x_bl.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c
index 61a7f45bfad84..ea4fa69e49a70 100644
--- a/drivers/video/backlight/lp855x_bl.c
+++ b/drivers/video/backlight/lp855x_bl.c
@@ -252,6 +252,8 @@ static int lp855x_bl_update_status(struct backlight_device *bl)
 	else if (lp->mode == REGISTER_BASED)
 		ret = lp855x_write_byte(lp, lp->cfg->reg_brightness,
 					(u8)brightness);
+	else
+		ret = -EINVAL;
 
 	return ret;
 }
-- 
2.39.2